The Old Customs House, also called the Old Post Office, was completed in 1874 and was Knoxville's first federal building. It held federal courts, excise offices and the post office until 1933.
It is a three-story Italianate building sheathed in East Tennessee marble, designed by U.S. government chief architect Alfred B. Mullett. As the city's population quadrupled, the building became crowded and was enlarged in 1910.
From 1936 to 1976 it housed Tennessee Valley Authority offices. Since its 2004 expansion it has been home to the East Tennessee History Center.